Motion-transmitting remote control cable assemblies suitable for transmitting force and motion, such as push-pull cables or Bowden cables, are used as motor vehicle transmission shift cable assemblies. A transmission shift cable assembly typically includes a flexible core element (the core wire or core or strand) slidably enclosed within a flexible outer sheath (the conduit). A conduit end fitting is at each end of the conduit, and the core extends through the conduit end fittings (also referred to as conduit fittings). In some designs, for example, at one end of the cable assembly (the shifter end), the core wire attaches to the transmission shifter selector in the cabin or passenger compartment of the vehicle, typically via a rod end fitting attached to that end of the core wire. In some designs, e.g., the cable resides in the driveline tunnel. In the driveline tunnel, engine compartment, etc., at or near the second end of the cable assembly (the transmission end), the core wire attaches to a controlled member of the motor vehicle's transmission, e.g., a movable lever acting as the gear selector arm or the like of the transmission. This end of the cable assembly typically must withstand a harsh environment during vehicle operation, often including elevated temperatures. A fitting at the transmission end, optionally referred to as a terminal sub-assembly, in some cases includes a core wire length adjuster attached to the transmission. The core wire length adjuster is used to adjust the length of the core wire, e.g., during original assembly of the vehicle or during maintenance or repair service to account for manufacturing tolerances build-up (or “build variations”) and the like. The terminal sub-assembly at the other end is secured to an actuator, i.e. a shift lever or other control member. Typically, the actuator and the controlled member each has a mounting pin, alternatively referred to as an attachment pin, e.g., a ball stud type attachment pin or a tapered pin or other suitable feature at a mounting point for suitable connection to the cable assembly, such that the cable assembly is able to transfer load or motion between the two mounting points. That is, moving the shift lever or other actuator member transmits force/motion via longitudinal movement of the strand within the sheath, to correspondingly move the controlled member and so shift the transmission. Each conduit fitting attaches to a corresponding bracket or other mounting fixture, support structure or the like, and a grommet may be used between them at the firewall separating the engine compartment or driveline tunnel from the passenger compartment.
The strand of a motion-transmitting cable assembly and its attachment pins and other mounting components can collectively have a relatively large dimensional tolerance range due to manufacturing variations and the like. In automobile transmission shift systems, this can result in a significant difference in fit and from one unit to the next, resulting in the possibility of relative movement between the fitting and the pin referred to as lash. In certain cases lash causes inaccuracy in the functioning of the transmission shift system. Additionally, these known terminal assemblies often have large installation loads (the forces required to attach the terminal sub-assembly to the pin or other mounting component) in order to obtain correspondingly high extraction loads (the forces required to remove the terminal sub-assembly from the pin or other mounting component). Traditionally, the problem of lash is mitigated by the use of an isolator at the interconnection between the pin and the terminal sub-assembly, designed to absorb vibration. Isolators must be made of a soft, resilient material that has significant give or resiliency to absorb the vibration, and as a result they can suffer wear and breakdown in areas were the force or load is concentrated, i.e. where the pin contacts the isolator. The material of the isolator, however, must be adequately resistant to deflection or compression set over extended usage periods.
The problems associated with controlling lash and installation and extraction forces are exacerbated by the harsh operating conditions at the transmission, typically inside a motor vehicle engine compartment or driveline tunnel, including, for example, the high temperatures which routinely occur inside the engine compartment and driveline tunnel. Present day specifications require some motor vehicle transmission cable assemblies at the transmission end, i.e., in the engine compartment or driveline tunnel, to function properly over extended use at 149° C. or lower. Because much of the heat given off around the transmission is directional, present day technology is to shield the cable from high heat instead of opting to change the cable. However, it has been discovered by the inventors hereof that such a solution is not optimal.
Accordingly, there is a need for improved transmission shift cable assemblies and components, which are suitable to meet more stringent conditions mentioned above for transmission shift cable assemblies, account for dimensional tolerance ranges of mating components, and are operative to reduce vibration during operation. There is also a need for motion transmitting remote control cable assemblies and end fitting for such cable assemblies, which require relatively low installation loads while maintaining relatively high extraction loads. There is also a need for motion transmitting remote control cable assemblies and end fittings for same, resistant to wear or breakdown at the area of the interconnection between the terminal sub-assembly and a mounting pin. There is also a need for terminal assemblies that are economical and simple to assemble and install with proper orientation.
It is an object of the present invention, to provide transmission shift cable assemblies and components addressing one or a combination of the above requirements or problems. Additional objects of at least certain embodiments of the present invention will become apparent to those skilled in the art from the following disclosure and detailed description of exemplary embodiments